The field of this invention is that of fuel evaporation heaters and the invention relates more particularly to a fuel evaporation heater for use in an automotive fuel supply system for enhancing fuel evaporation without unduly interfering with the flow of an air-fuel mixture to an automotive engine.
It has become common practice to mount a self-regulating electrical resistance heater between the air-fuel induction passage of a carburetor or the like and the intake manifold of an engine for enhancing fuel evaporation in an air-fuel mixture being furnished to the engine, thereby to improve fuel use efficiency and engine driveability and to reduce the emission of exhaust gas pollutants. Typically for example such a self-regulating heater has comprised a multipassage body of a ceramic material of positive temperature coefficient of resistivity (PTC) which has been mounted in the air-fuel passage of a carburetor so that the air-fuel mixture being furnished to the engine is directed through the multiple passages of the ceramic body to be heated as the air-fuel mixture is fed to the engine. In those cases where such a positioning of the multipassage heater body has been found to unduly interfere with the flow of an air-fuel mixture to the engine, the heater has been disposed within the intake manifold of the engine so that the flow of the air-fuel mixture is directed onto the heater but is also adopted to flow more freely over and around the heater into the engine. In such cases, where fuel has tended to condense on the walls of a carburetor passage during engine start-up on a cold day or the like, or where the configuration of the heater has differed from the cross-sectional shape of the air-fuel passage of a carburetor or the like, it has been proposed that a tube be arranged to intercept fuel condensed on the air-fuel passage walls and to extend that tube into the manifold to direct such condensed fuel onto the heater at a location inside the manifold. It would be desirable if such a fuel evaporation device could be provided with a sturdy, versatile, low cost construction adopted to achieve such new and advantageous results.